According to this
article on dpreview:
Weather-proofing topped the list as the most desirable feature camera buyers are looking for, according to a recent survey. J.D.Power’s Camera Usage and Satisfaction Survey revealed that, while point and shoot, and DSLR camera users are missing this attribute in their cameras, a majority of ultra compact users hope for more internal memory in future models. The survey also reveals that Internet product and review sites are the most important resource in guiding buyers with their market research.
Owners of Point and Shoot, Premium Point and Shoot, and DSLRs all placed weather- and water-proofing at the top of their wish-lists, while Ultra compact camera users want to see internal memory increased to several Gigabytes, rather than the Megabytes typically offered at present.
Looks like Pentax is one step ahead, already offering weather-proofing on the K200D as well as the K20D.
I've been in light rain with my K10D and it's reassuring to know that the camera is weather-sealed.